Unspoken Rules
by Thiaf
Summary: Saniwas shouldn't be intimate with swords from a different citadel; it was an unspoken rule. When Sengo's master rejects him, he decides that some rules are worth breaking.
1. Chapter 1

Scenes are written out of sequence. They've been numbered if you want to read chronologically.

The Mutsunokami/Sen scenes are in the next chapter.

There are only minor hints of Monoyoshi/Gotou.

* * *

3.

Every sword belonging to Sen and Rinko sat in the Ashina Citadel's great hall. The sages sat atop the dais.

Currently, Sen was reading off a piece of paper, listing the accomplishments her household achieved this year.

Rinko originally pitched the idea to celebrate their second year as saniwas together in her citadel. She wore a pink kimono and had touched up her hair and face for the occasion. Her clothes and hair pieces had flower motifs to fit the spring season. Sen, however, wore her usual sage attire. Rinko bit her tongue to prevent yawning.

For entertainment, her eyes wandered over Sen's swords. It was an unspoken rule that saniwa shouldn't sleep with swords from a different citadel. They should never have to grapple with their loyalty, which belonged solely to their master. Rinko, nonetheless, indulged by looking at them. She glossed over the tantous and wakizashis and settled on the uchigatanas. Mutsunokami was listening attentively.

She first saw him a week after Sen and Rinko manifested their first swords. Sen brought Mutsunokami, Sayo, and Gokotai to Rinko's home to meet Kashuu, Aizen, and Imanotsurugi. Mutsunokami had everything that Sen ogled. When they apprenticed and lived in the same shrine, Rinko had went to Sen's room to borrow a book. When she opened the item, clippings of well-muscled men fluttered down like leaves in autumn. Rinko had a good long laugh that night. She had finally found evidence of Sen's lust.

Sen and Mutsunokami were going to fuck eventually, Rinko knew. Gossip confirmed it, as far as she was concerned. Sen finally had a man she could trust with all her confidence and most personal thoughts. And yet, during the feast last night, Sen was eating her meal in peace while Hirano poured her tea. Rinko, on the other hand, leaned against Shokudaikiri and rubbed his thigh. Some of Sen's swords side-eyed Rinko. Her tantous knew better than to ask any questions, but some huddled together, whispering about Rinko. Sen's swords would know that displaying affection was normal, if she stopped being a covert pervert.

Rinko gazed over the other uchigatanas, until she met a pair of red eyes staring back at her.

Sengo winked at her. Rinko raised an eyebrow. Did he know what she was thinking?

1.

Sengo stood facing the shoji of his master's study. He knocked on the wood.

"Who is it?" his master's voice came from inside.

Tonbokiri, after Sengo manifested, had mentioned that their master was a woman; that would make for great entertainment.

"This is Sengo Muramasa. I'm the so called demon blade."

"Please, come in."

He slid open the shoji. She was more lovely than he had imagined. She had long black hair and fair skin. She wore the modest white and red saniwa garb. He wondered what wonderful things she hid under her clothes. Beauty was wasted if it was never seen.

"I am Ueda Sen," she smiled and nodded. "As the head of this citadel, I welcome you."

 _Sen_ , he chuckled and knelt, facing her. "We share the same character in our names."

"Yes, my mother had given that to me...," her eyes glimmered with a touch of nostalgia. "If there is anything you want or need to know, please ask me or anyone else."

"I have two questions," Sengo crawled closer to her.

Her expression changed to confusion. She was so innocent; Sengo would have to teach her the benefits of being wicked. His face was inches away from hers.

He tugged at the collar of his attire, revealing skin. She stared at his exposed chest.

"What are you thinking about, Master? Shall I undress?" having this form would let him explore the full pleasures of the human body. This woman, his master, would be the first he would share these sensations with.

Sen said nothing. Perhaps she needed some coaxing. Who knew what hesitations or fears she absorbed about sex. She had to learn to let go of those silly morals. He raised a hand towards her face, ready to touch her chin.

"...Muramasa."

"Yes?" he stilled his hand.

"You must return to your rooms. You will be participating in chores tomorrow," her face showed no fear or disdain. She had faced much more fearsome monsters than him.

His lips twitched. Sengo pressed his hand against the tatami mat. So, she was uninterested, but he would enchant her soon.

"As you wish, Master," Sengo shifted away from her and bowed.

4.

Swords and saniwas were out in the gardens this morning to view the sakura blooms. Gotou, Sen's attendant, held her hand and led her about, pointing at one tree and then another.

Rinko sat with Monoyoshi under one of the trees. Sen had inherited the Awataguchi clan, fortunately. Rinko could never handle tending to so much children in her home.

"Master," Monoyoshi leaned towards her. "Someone is approaching us."

Sengo was walking towards them. Rinko knew what he wanted from her. She would give him the chance to get to know her.

"Leave me for now," she said. "Spread your luck amongst everyone."

Monoyoshi excused himself and left her. He went off to speak to Sen and Gotou.

"Ashina-sama," Sengo stood a few feet away from her. He was grinning, but Rinko didn't return any pleasantries.

"Hello," Rinko said. "How are you adjusting to your new form?"

"It's a wondrous experience," he swayed his hips. Sengo's habits were well known about the town. Rather than talk about sex, she would see how he addressed personal subjects.

"I have heard that you Muramasa blades have driven your wielders mad. Something about your smith polluting his works."

"Hm, if you wish to believe in a myth, then you can," his smile invited her eyes to wander. His top garment hugged around him, showing his bulging chest. His arms were bare for everyone to see. "Shall I undress and let you judge me?"

He tugged the side of his hakama. Sakura petals rained down on them. Rinko had no hesitations about bedding Sengo, but he didn't belong to her.

"You can die trying to strip here," Sen would dismantle Muramasa if she was angered enough. In truth, death was better; it implied that you had lived. You could leave something behind in this world. Dismantling would make your whole body disappear. "I want to fully examine your beauty, but will that upset your master?"

"Should it matter? These unspoken rules you humans follow restrain yourselves from living a full life."

The life of a lawless demon was an envious thing. He did as he liked and had no worry about reputation or upholding family honour. Had Sengo been born human originally, he would understand the perils of walking about this land.

"That is very true, Muramasa. I know what we can do to rectify this complicated existence."

5.

"This is a good place," Rinko opened the shoji. The room was furnished in a Western style, with chairs, a couch, and a study table. She stepped into the room and stood a top a chair. "It was made in case we received foreign guests, but it has been barely used and is down an empty hallway."

"What have you done in here?" Sengo closed the shoji and walked to her. They were inches away from touching. He wanted to know how bad she was. She had a little smile on her face.

"Kogitsunemaru and I roleplayed. I was an unsatisfied imperial wife who was spirited away to an unknown place. He was a fox god who mated with me all day and night until I was carrying his cubs in me."

"My, what a wanton woman you are," her story was already making him hard. He nuzzled his face against her chest, feeling small breasts. He smelled orange perfume on her. Were her swords conditioned to be aroused when they smelled that scent? "You're utterly fearless."

"We Ashinas are descended from a goddess," she ran her hands through his pink hair. "I have divine blood. Demons do not worry me; they should fear me."

"They are whatever you make of them," he kissed her exposed neck. "They only have power if you believe in them. What do you think about cursed swords?"

Rinko kissed his cheek and then his lips. He opened his mouth, so the tip of their tongues could touch. The were only teasing each other. The main event was yet to come.

"I want to know if you can fuck as well as a blessed one."

"I'll let you decide," it was good fortune to have found this lady so in tune with him. If Sen was uninterested in him, then so be it.

He wrapped his arms around Rinko's waist and carried her.

Rinko giggled as he set her down on the table. Her hands felt his hard arm muscles. She wanted to pour honey on him and see his skin glisten. Seeing him lick the substance off of him would make for a good show. Next time, food would be involved. Sengo never objected to any sexual act.

Sengo tugged at the back of her obi. Rinko raised an eyebrow. He knew how to undress a lady? He must have learned how to do it from past encounters with people, but who were they? Sen rarely dressed up.

"You may undo my sash. Now, tell me," her palms pressed against his chest. Her finger circled his nipple. "Whom have you made love to?"

A single laugh escaped his lips.

"As many who are willing," he smiled and untied her obi.

"Is your master one of them?"

Sengo paused. Perhaps it hurt his pride to be asked or maybe he was planning to deny any relations with Sen. Rinko already knew the answer, though she just wanted to know if Sen had done anything risky.

"Sorry," she withdrew her hands. "I should not have -"

"No, it's fine," he pulled her sash off. Sen had a criteria for lovers that he couldn't meet. "She can bed whomever she pleases."

"She is very careful," Rinko lie against the table surface. "But that is enough about her. We are all about each other now."

Sengo parted her kimono. The cool air made her shiver.

"I shall warm you up," he pressed a palm against her bra. He massaged her breasts in circles, pressing on the places women liked.

Rinko arched her back as he made his ministrations. Her pleasure washed over her body as he squeezed her. She wrapped her legs around his waist and pulled him close to her.

"What's the matter?" he smiled wickedly. His hands gripped her hips and he grinded his erection against her.

 _This snake will not get the better of me_ , she thought. She was the heir of a powerful clan; a mere sword couldn't undo her. "I was with Nikkari and Kikkou once. They took turns pleasuring me with their mouths to decide who was the better performer."

"Who was the victor?" he ran his thumb up and down her clothed nub.

"I-it was a draw; they both made me come twice."

He slipped her panties off. Hopefully, he would outdo Kikkou and Nikkari. Perhaps all three of them could have Rinko at the same time.

"A woman's body is an enviable thing."

When Rinko and Sen apprenticed together, they occasionally bathed in an onsen. Sen got taller, her curves formed, and her breasts grew out. Rinko, two years Sen's junior, hoped she would mature soon, but she grew only a little bit and was near flat chested. She supposed that the gods punished her for being too confident about everything else in her life. Regardless, Rinko's lack of physical endowments forced her to be brave against imposing people.

Sengo lowered himself and kissed the hair between her legs. He licked downwards until his lips pressed against her entrance.

Rinko pressed her thighs against his head. She felt his tongue slip inside of her. Rinko grabbed his hair and pressed him against her nether regions. He was only permitted into this room to satisfy her and she damn well reminded him of that fact. She felt him grinning against her skin.

Sengo sucked up her wetness. His tongue slithered inside of her, finding all the right places. His thumb circled her nub, increasing Rinko's pleasure. Her body already tensed up and her breathing quickened.

Fucking a sage was something else compared to being with another human. There was this overwhelming need to serve the saniwas well and forever, until one's spirit was spent. No sword could resist loving his master the moment he met her. What would it be like to have the sages at the same time?

Rinko gripped his hair then. She cried out and clenched around his tongue. Her liquids poured into his mouth and he lapped up every drop. She tasted tangy, like so many others.

He listened to her catch her breath as he licked the wetness seeping out of her. A minute later, her thighs went limp and he was released. So, this was how powerful women could be undone. Sengo would remember where he touched her to bring her to ecstasy for next time.

Rinko was exhausted, but she kept her eyes on him.

"We're only half way to the end, Ashina-sama," Sengo untied his hakama. He took his erection out for her viewing.

Oh, he was big. While Sengo stroked himself, his member enlarged and the veins thickened. This excited Sengo the most; seeing his partner captivated by his performance, being the centre of attention. He only wanted to have sex more and more. Why did humans hesitate so much when it came to carnal desires?

"What do you want me to do?" he pressed the side of his cock against her thigh. He rubbed his tip up and down along her skin, smearing his precum on her.

Rinko knew they would meet each other in secret again; a room could be rented or he could sneak into her citadel. Right now, she could request anything from him.

"Come on me," she pointed at her belly. "I want to see how much I can milk out of you."

"As you wish," Sengo quickened his pace. He grunted as his cock pulsed within his grasp. He would show her what he was made of. Then, he climaxed and came over her. His seed splattered out and streamed down her skin. Rinko gasped as she felt his semen spread about her in streaks. There was much more seed than expected.

Sengo leaned forward and pressed his hands on the table. She watched the demon pant. His sweaty, heaving chest was a wonderful view. He still had that lustful look in his half-lidded eyes. They had plenty of hours left to fool around. He was going to clean off the mess he made.

* * *

Sengo, in my eyes, is the type of person that challenges what is considered acceptable in society. He will do as he likes, unafraid of conforming to norms.


	2. Chapter 2

6.

Sen stared up at her guestroom's ceiling. Each tile had a different flower painted on a golden background. She turned over onto her side on the futon. It was still dark, yet she heard birds chirping outside.

"...ya'r still awake?" Mutsunokami yawned. He rolled over and rubbed her bare shoulder.

"I just awoke," she said.

Rinko and Sen had planned their second anniversary celebrations for weeks. During that busy period, she had no time to couple with her lovers; Ichigo made no sign of impatience, but Mutsunokami tried to catch her attention and even asked directly if she had time for sex. They all had to wait.

Last night, Mutsunokami finally met Sen in her room and they unleashed their pent-up desires for one another. Their bodies joined together and they made love until they were spent. Even now, her legs were limp from their activities.

"It's still early, ya know?" Mutsunokami kissed the back of her head. Her hair was smooth against his face.

"It is," Sen placed her hand over his and guided him to her breasts.

"Heh," Mutsunokami circled a finger around her nipple. He squeezed her hard nub between his fingers. He listened to her soft sighs, her muttering his name. He would make Sen scream by the end of this.

They were interrupted by banging footsteps outside and then loud rapping on the shoji.

"Ueda-san!" Nagasone said. "I've got orders from the Time Government."

Sen tried to sit up, but Mutsunokami had an arm around her torso. He glared at the entrance. What did he think he was doing?

"P-please wait a moment," she turned her head to Mutsunokami and whispered. "I have to go."

Mutsunokami frowned, but he released her.

Sen put on a robe and headed out to the room's entrance. She parted the shoji by an inch.

Mutsunokami watched Sen converse. The Time Retrograde Army was spotted near the Ikedaya Incident again. Sen, instead of Rinko, should send a squad, as she had the most tantous.

 _He doesn't deserve to see ya in a nightrobe_ , Mutsunokami thought. During daytime celebrations, Sen's gaze lingered on Rinko's swords, like Kogitsunemaru and Nihongou; Mutsunokami didn't mind, but Nagasone was a different matter.

"I will dispatch a unit within an hour," Sen bowed her head to Nagasone and then shut the shoji. She turned back to Mutsunokami. She stood where she was, silent and observing him. She knew exactly what made him so protective a moment ago.

"Aren't ya comin' back to bed?" Mutsunokami forced a smile on his face.

"...the Shinsengumi disbanded centuries ago. Their swords are our allies."

He flinched at Sen's words. He had good reason to be on edge. They were guests who suddenly heard someone running towards her room. It was no less than Kondo Isami's sword that interrupted them; it paralleled Sakamoto's doom far too well.

Sen walked over to her writing desk and started composing a list.

Mutsunokami lie on his back. He knew she was right. He would work with Rinko's Shinsengumi swords if he had to, but that didn't mean he needed to be friendly with them.

"These are the tantous I am sending," Sen held up the paper. "Can you get them?"

Mutsunokami couldn't refuse her.

2.

Sengo and Mutsunokami were on night watch duty. Mutsunokami pointed his binoculars up at the black sky.

Sengo sat on the grass. He was in the presence of the first sword in the Ueda Citadel. Mutsunokami and Ichigo Hitofuri were Sen's only partners, as far as anyone knew. How had Mutsunokami climbed over the walls that their master built around herself?

Everytime Sengo saw his master after their first encounter, they were never alone in the same room and she behaved as if he hadn't tried seducing her. A straightforward rejection would have been enough. Sengo would only ravish her if she wanted him. When he was about in the markets and spotted anyone's lingering stare on him, he would approach them and let them know he welcomed further admiration; this usually resulted in a good amount of sex afterwards.

"Ya can see a lot more stars with these," Mutsunokami lowered the binoculars. "It's got heat _and_ night vision. I'm goin' to give these to Ya-chan. It should help him with scoutin'."

 _Ya-chan_? Sengo thought. "Do you mean Yamanbagiri?"

"Yeah, the captain," he said. "I've got nicknames for everyone."

"So," he started chuckling. He could test Mutsunokami now. "Will you call me 'Sen-chan'?"

"Ah," Mutsunokami paused. His friendly face wavered for just a moment. He scratched his head. "'Sengo-kun' sounds better, don't ya think?"

"Of course," Mutsunokami's reaction confirmed that he called their master 'Sen-chan' while he fucked her. Sengo sighed. "It's rather troublesome to have a name similar to Master's."

"Sen's a good name," Mutsunokami sat down on the grass. "It's short and sounds nice."

"She never explained to me why her mother chose that name."

"I'll tell ya," he lie down and gazed at the moon and stars.

Sen's parents had two sons first. Two children were enough for her father, but her mother insisted on having one more child, one last chance. Her mother was descended from the Ashina family. She insisted on having a girl, even though no one remembered why it was important to have one.

"I'll have a daughter," she said. "Even if it takes me a thousand tries."

It only took her three times to have a girl. The baby was given the character for a thousand: Sen. All her mother's efforts to deliver her daughter into this world was represented in that number.

After the historical revisionists began experimenting on swords, the world rediscovered why the blood of Ashina women was so important. They had the power to manifest weapons into human form. These abilities were passed on only from mother to daughter. Sen and Rinko, compared to their mothers, had an exceptionally high amount of spiritual power; the gods had given them their gift, knowing the sages were needed to combat the revisionists.

Sengo was silent. Mutsunokami, dreamy-eyed, stared at the sky. He remembered that night when Sen told him about her name. Mutsunokami had lie against her lap as she patted his head. She loved his unruly hair. Her father suggested she be named 'Chiyo' instead. 'Sen' was a rare, sad name that evoked the tragedies of Senhime from the Tokugawa family, but her mother was stubborn. Mutsunokami was glad Sen kept her original name.

"Yoshiyuki-san! Muramasa-san!" Gotou ran out of his tent. "I'm ready for my night shift."

Honebami followed after his brother.

"Please, rest well," he said to the uchigatanas.

"We haven't seen the bad guys," Mutsunokami stood and held the binoculars up. "Try usin' this tonight. I'm goin' to ask Master to buy more of these."

Sengo still didn't have any of the answers he wanted. Though, he knew for certain that Mutsunokami had Sen's trust like no one else.

7.

Rinko and Nagasone stood on the veranda, facing the courtyard. Shinano, Gokotai, Akita, Hakata, and Yagen, dressed in their kiwame attire, stood by the time travelling device.

Behind Rinko, in a room, were Sen, Gotou, and Mutsunokami.

"General," Gotou beamed up at Sen. "I'll get back as soon as I can."

"You do not need to rush. It is more important that you all return safely, with little injury."

Gotou opened his mouth, but then closed it. He had given her the wrong answer. He had thought about seeing the fireworks tonight and speaking with Monoyoshi. He was powerful for a wakizashi. Gotou wanted to learn how to be as skilled as Monoyoshi.

Sen had yet to send him on his kiwame journey because of his inexperience. Since Gotou was the captain, she hoped he would grow quickly as a fighter.

"Give him the omamoris," she said to Mutsunokami.

Mutsunokami handed the six charms to Gotou. Mutsunokami was silent and unsmiling, but Gotou said nothing. Instead, he thanked them and made his way to his brothers.

Sen stepped out onto the veranda, standing beside Rinko.

Gotou set the date on the time travelling device. Gotou waved as his team was surrounded by magic and light. And then they disappeared in a flash.

"Thank you for handling this, Sen-chan," Rinko clapped her hands. "They will be fine."

Sen nodded. Her tantous had been to the Ikedaya Incident numerous times.

"I am returning to bed," Rinko rubbed her neck. "Come, Nagasone."

Rinko walked off. Nagasone said his farewell to Sen and then followed after Rinko.

Dawn had arrived; the sky was blue and the clouds red. The sakura trees were at their peak bloom. Everyone deserved to have a good viewing today. Tomorrow, Sen and her swords would return home. It was unrealistic to expect that their growing households could join together again like this.

Mutsunokami wasn't looking at her. His arms were crossed and he eyed the wall on his right.

"Mu-chan...," she turned and stepped towards him.

"I'm goin' back to my room," he said. He had disappointed his master. It was best to keep his distance from her for a few days. She had Ichigo, if she needed someone to warm her bed. He could spend a bit more time with Yamanbagiri too.

"...Mu-chan," now she was standing close to him. He needed to know she wasn't angry. She pressed a hand on the side of his face. Everytime they touched, there was a tinge of warmth. It was more than physical contact; there was spiritual power that ebbed out of her and it pulled him towards her.

Mutsunokami turned his head to face her. Sen had a sad, sympathetic look. This was unexpected. Why was she so glum?

"It must have been hard to witness Sakamoto's death," she could only imagine the turmoil, self-loathing Mutsunokami faced when he recalled that incident. He could've protected Sakamoto if he had been anything other than a sword. He had contemplated how things could've been different, yet he had to protect that history. He had to know he was undoubtedly important to her, no matter what. "You love him so much."

All swords were summoned for the sole purpose of fighting against the revisionists. She didn't have to care this much about his past, yet here she was, acknowledging his humanity. He could make mistakes, so long as he learned. What did he do to deserve being chosen as her first sword?

He chuckled softly.

"Ya don't have to be nice, ya know?" he leaned forward, pressing their foreheads together. He wrapped his arms around her. She was always soft and warm. Her heart beat lightly against his chest. In this body, he had experienced so many sensations with her. He thanked the gods that he and Sen were somehow able to meet each other and share everything together. "I'm not leavin' yet. Ya wanna stay?"

She knew what he really meant. Sen tilted her head up to let him kiss her. They coupled in sight of the sakura blooms.

8.

Gotou's team completed their missions in four hours.

He was standing in the gardens at night, facing Sen and Mutsunokami. His master had dressed up in a kimono; she resembled a princess, like Chiyohime. Gotou gave an informal report on his sortie as they sat on the veranda.

"I beat the oodachi like this," he curled his empty fist, like he was holding his tantou, and stabbed the air repeatedly. He kicked and jumped, trying to re-enact the best moves. It only took him two attempts to perform a perfect somersault.

"Ya should try teachin' me how to do that," Mutsunokami laughed aloud.

"Good work," Sen smiled. "You and your team did well."

Gotou continued to copy what he did in Kyoto. If he showed how skilled he was at leading his brothers, she may send him off on his kiwame training.

"Gotou," Ichigo stepped towards them. "We're lighting the fireworks soon. Master, may he leave you for a few minutes?"

"He may go," Sen said.

As Ichigo left with Gotou, he mentioned that Monoyoshi needed someone very tall to help him with the fireworks. Gotou promised that he could be of use.

In the garden, Rinko held onto Nagasone's arm and chatted continuously. She was swaying a little bit and her face was red, despite her makeup. She stumbled towards Sengo. He caught her in his arms. They clung to each other for much too long. Her hand ran down his arm. They both stared at each other with wanton grins. Sen had seen that face often while they apprenticed together. She had no reason to disprove their relations and she knew that Rinko, of all people, could handle Sengo. He was too fast and bragged about his conquests with the other people; Sen could never trust him as a partner.

Firecrackers started popping up in the sky, scattering sparking light above them.

Sen's household, along with Rinko's, mingled together and cheered at the sky. Monoyoshi complimented Gotou setting off fireworks for the first time. He had also watched Gotou's demonstration infront of Sen and Mutsunokami and thought Gotou looked very cool. Gotou had a little smile and blush on his face, though the night covered his redness. Sen was reminded of how she could be when she was infatuated, all flushing and flustered. Gotou and Monoyoshi could learn and grow with one another in time.

"It has been two years since this war started," Sen, seeing everyone so joyous, wanted to make sure that the future would continue to be happy. There were decades of work ahead for her, Rinko, and their swords.

"Sen-chan," Mutsunokami patted her back gently. The revisionists never stood a chance against the likes of his lover. He looked forward to all the time they had left with each other. "Ya've done really well."

* * *

Sen, Sengo, and Chiyo all have the character for a thousand in their names: 千. Depending on context, it's pronounced as either 'sen' or 'chi'.

I personally picked 'Sen' as her name because it's short and has a nice sound.

The Ashina clan and the origin of their powers are my head canon. I see the powers of the saniwas as inherited, though others may imagine it differently.


End file.
